The major focus of the 1984 Gordon Research conference will be: The molecular basis of the contractile process. The work to be presented will deal with mammalian skeletal, cardiac and smooth muscle as well as with selected non-muscle contractile systems. In the past three years significant progress has been made in a broad range of areas in muscle research. Particular emphasis will be given to new findings on the DNA sequence of several myosin heavy chain genes in C. elegans, cardiac and skeletal muscle. The protein sequence of rabbit myosin heavy chain is close to completion specifying the location of several key post-translational modifications. A high resolution crystal structure of G-actin is imminent and promises to aid in defining the structure of F-actin filaments. Chemical cross-linking studies combined with limited proteolysis have given new insight into the possible domain structure of myosin and to the location of the actin binding site on myosin. New photoaffinity labels are defining the ATP binding site of myosin and are providing covalent probes to be used in mapping the topography of myosin. New applications of fluorescent and spinlabeled probes as well as time-resolved low angle x-ray diffraction are determining cross-bridge orientation during rigor, relaxation and contraction. The possible regulation of contraction of smooth muscle by systems other than light chain phosphorylation will be addressed. A major theme will be correlation of biochemical information from purified systems with similar studies in skinned fibers and actomyosin threads. It will be the purpose of this conference to summarize the major areas of progress during the past 3-5 years, and to point the way to those areas which should prove productive for research in the immediate future. The conference will include a limited number of formal presentations with emphasis being placed on discussion and informal interchanges. Ample use will be made of poster presentations and a specific session will be devoted to a discussion of the material presented on the posters. This conference has become a major triennial meeting which attracts the leading research workers in muscle research from around the world. In allowing scientists of diverse backgrounds to focus on the molecular mechanism of muscle contraction for a week, this conference should help to open new areas of research as well as provide a meaningful reexamination of previously accepted ideas.